Can You Get Schistosomiasis More Than Once?

Yes, you can absolutely get schistosomiasis more than once. Curing a previous infection does not make you immune. If you travel back to an area where the disease is common and come into contact with contaminated fresh water, you can be infected a second (or third) time ^[1][2].

Why Immunity Doesn’t Last

Unlike some diseases such as chickenpox, your body does not develop a permanent, protective shield (often referred to as sterilizing immunity) against the parasitic worms that cause schistosomiasis ^[3][1].

While people who live their whole lives in areas where the disease is common might develop a very small amount of resistance over decades, this protection is incomplete and is never enough to fully prevent a new infection ^[3][1]. Therefore, travelers, expatriates, and visitors returning to see family remain highly susceptible to reinfection ^[4][5].

The Limits of Treatment

The standard medication used to treat schistosomiasis, praziquantel, is highly effective at killing the adult worms currently inside your body ^[1]. However, it is a treatment, not a vaccine ^[2][6]. It works to clear your current illness but leaves your system quickly, leaving no lingering protection behind ^[7].

Additionally, praziquantel only targets mature worms. If you are treated too soon after exposure, immature worms can survive the medication, mature later, and eventually cause symptoms ^[1]. Patients sometimes mistake this survival for a new “reinfection.” Regardless, the moment you are actually exposed to contaminated water again, new microscopic parasites can penetrate your skin and start a brand-new infection ^[4][8]. Currently, there is no approved vaccine for schistosomiasis, though researchers are actively trying to develop one ^[1][2].

How to Protect Yourself on Future Trips

Because you have no built-in immunity, your best defense on your next trip is avoiding the parasite entirely ^[7][9]. Here are practical ways to prevent a new infection:

• Avoid all fresh water: Do not swim, wade, or bathe in freshwater lakes, rivers, or streams in areas where schistosomiasis is common (such as parts of Africa, the Middle East, South America, and parts of Asia) ^[10][7].
• Stick to safe water: Swimming in the ocean or in properly chlorinated swimming pools is safe ^[9].
• Treat bathing water: If you must use fresh water for bathing, boil it for at least one minute to kill the parasites, and let it cool before use ^[7]. Water stored in a completely sealed tank for 1-2 days without snails is considered safer, but boiling is the only completely reliable method.
• Dry off immediately: If you accidentally come into contact with untreated fresh water, dry yourself vigorously with a towel. While this might help prevent the parasite from entering the skin, it is not foolproof ^[9][11].

What to Do After Your Trip

If you suspect you were exposed to untreated fresh water while traveling, inform your doctor or a travel clinic upon returning home. Because you can be reinfected, medical guidelines often recommend follow-up testing for returning travelers 6 to 8 weeks after their last potential exposure, even if you feel completely fine ^[12][13]. This ensures any new infection is caught and treated early before complications arise.